Overload drive release



0a. 20, 1953 w, BACH 2,656,185

OVERLOAD DRIVE RELEASE Filed March 17, 1951 INVEN OR ATTORNEY Patented Oct. 20, 1953 7 2,656,185 OVERLOAD DRIVE RELEASE John William Bach, Port Chester, N. Y., assignor to Pitney-Bowes, Inc., Stamford, Conn., a corporation of Delaware Application March 17, 1951, Serial No. 216,210

7 Claims. (01. 271-41) This invention relates to sheet handling devices and particularly to sheet separating and feeding devices of the type having a sheet separating roller which is opposed by a relatively fixed abutment and is usually driven through an overrunning clutch.

In the sheet handling art it has been known to provide a friction roller working in cooperation with a closely spaced, relatively fixed, high friction surfaced abutment for separating workpieces, in the form of sheets, from a stack and forwarding them one at a time to be worked upon.

Usually the abutment is adjustable to provide for the proper handling of sheets of different thicknesses. It sometimes happens, due to various causes, that a plurality of sheets will be driven between the starting roller and the abutment instead of the single sheet ordinarily intended, and that these sheets will jam the machine by becoming tightly wedged in this position. The resulting jam, is in fact, frequently so tight as to be quite diflicult for the operator to free, and working upon the same, the overrunning clutch associated with the drive for the starting roller can be easily damaged if excessive force is applied to the mechanism.

The present invention has for its object, therefore, the provision of relief means in the form of an overload drive release for preventing the sheets from jamming tightly between the starting roller and the abutment.

It is a feature of the present invention to provide relief means of such a nature that the starting roller is automatically disconnected from its drive at a predetermined degree of jam pressure whereby the feed of the starting roller will be immediately stopped and the jam allowed to progress no further. The jam is thus allowed to reach a preliminary stage only, and hence involves sufficiently light pres-sures such that it can be readily freed by the operator without exerting forces on the machine parts of a magnitude sufficient to damage the relatively fragile structure of the overrunning clutch.

Since the degree of jam at which the relief means goes into operation must be predetermined with reasonable accuracy, it is another feature of the invention to provide a relief means of sturdy and simple structure which can be preset when installed and which neither re-- quires adjustment by the machine operator, nor is likely to materially alter its setting with continued use. I H l Still another object of the invention is the provision of a relief means for a sheet separating and advancing device which is simply arranged for ready installation on machines already in use, and which is highly economical by reason of the small number of parts and operations required to accomplish its construction.

For purposes of illustration and explanation the invention is shown in detail in its preferred form in the accompanying drawings, wherein:

Fig. 1 is a diagrammatic longitudinal sectional View of the machine of the invention with parts broken away, illustrating the operation when a single sheet is separated and advanced in the normal manner.

Fig. 2 is a view similar to Fig. 1, slightly abridged, and illustrating the operation of the parts during the occurrence of a jam.

Fig. 3 is a compressed detailed view to a slightly larger scale and partly in section of the starting roller and its shaft shown in Figs. 1 and 2, taken from the left and looking towards the right in Fig. 1.

The present invention deals with sheet separators and feeders employing a friction roller which cooperates with a fixed abutment, and is illustrated for convenience in connection with the four roll buckle type sheet folder. The machine comprises a frame .(not shown) upon which are rotatably mounted the usually cooperating folder rollers ll, [3, l5 and H. The rollers cooperate 1 in a known manner with the uppe and lower buckle chutes l9 and 2| to produce one or more creases in a sheet-like workpiece as the same is fed through the machine.

Sheets S are held in the form of a stack in the supply holder and guide 23. The separating and advancing means, indicated generally by reference character 25 is for the purpose of separating one sheet S from the stack and projecting the same forward to a position Where it can be engaged by the first pair of folder rollers l I, 13. The separating and forwarding means 25 includes a starter roller 21 which has a high coefficient friction surface. The roller 21 is mounted on and driven by a shaft 28 which is rotatably mounted on the frame of the machine. A gear 34 which forms a part of the driving train connecting the shaft 29 with a motor (not shown) is arranged adjacent one end of the shaft 29 and has a cylindrical hub 33, the outer surface of which coincides with the cylindrical extension of the surface of a hub portion 35 on shaft 29, as is best seen in Fig. 3. These two hubs form parts of an overrunning clutch which is completed by a helical spring 31 long enough to embrace both hubs. The spring is secured to hub 35 on the shaft 29, and is so configured as to exert a light radially inward force on the hub 33 to maintain the inner portions of its convolutions in frictional contact with the hub surface. The spring, as viewed from the right hand end of Fig. 3, is Wound in a clockwise direction starting with the near end, and thus serves to make firm driving contact with the hub 33, when the same is turning in the normal counter-clockwise direction and when the roller 2'! is being driven thereby. Since rollers l3, travel at higher speed than roller 21, they will tend to drive the latter by means of the forwarded'sheeti when its leading edge reaches their nip. .Such driving vac- 1 tion will be permitted, for when the hub 35 turns more rapidly than the hub 33 in the counterclockwise direction, the grip of' the spring "3''! on hub 33 is loosened and the shaft 29 is permitted manner to a value suited to the thickness of the particular sheets being handled, and so that only one sheet at a time will be forwarded by the device 25.

The normal use of a sheet separator of the type with which this invention is concerned rel-.

quires that the supply stack be shingled slightly by the operator before bringing the edge of the same into contact with the separating means. For proper operation the shingling of the sheets must be in such a direction that the upper sheet of the stack is foremost, as shown in Fig. l, and is in a position to be gripped first by the friction surface of the roller 21. If the operator inadvertently shingles the stack in the wrong direction with the lower sheet having the greatest projection, several sheets at the foward end of the stack will be drawn at one time between the surfaces of roller 21 and abutment 39 in the manner illustrated in Fig. 2. When this condition occurs, the roller 27 in effect draws a wedge of paper between itself and the surface of the abutment 39. As the wedge thickens, the friction load against the surface of the abutment 39 increases very rapidly to a point where the motor will finally stall if the operator does not operate the stop switch in time. If the machine does become jammed in this fashion, it would normally be necessary for the operator to attempt to withdraw the paper wedge from between the surfaces of roller 21 and abutment 39. The wedging action, however, takes place so rapidly that the paper is usually very tightly jammed before the machine can be stopped, and frequently requires extraordinary measures such as tearing of the paper or gripping the same with pliers in order torelieve the jam. Strenuous clearing measures of this nature as well as the attempt to reversely rotate the drive mechanism by hand particularly places a load on the relatively fragile overrunning clutch mechanism described above, with the result that the spring 31 is frequently broken during the jam clearing process.

character 43 is introduced into'the drive forthe.

4 roller 21. This consists of a loose mounting of the roller 21 on the shaft 29 to ther with means for providing a connection therebetween which is subject to automatic release upon overloading. This connection includes a collar 45 integral with the roller 21 and having an aperture 41 slidably carrying a pin 49. The aperture 4'! is arranged to line up with a recess 5| in asurface of the shaft 29, and the pin 49 is normally urged into the recess 5| by the end of a leaf spring 53 mounted on the outer surface of the collar 45, for

example,, by screw 55. The inner end of pin 49, and the recess 5| have abutting surfaces, one of which has a'cam configuration such that forced relative rotation effects their disengagement. In the preferred form of the invention illustrated, both parts are so configured. The shapes of the inner end of the pin 49 or of the cooperating recess 5|, as well as the strength of the spring 53, may be so adjusted that torque of any desired predetermined value is required to force pin 49 out of the recess 5| and permit slippage of roller 21 on shaft 29. This value of torque is so determined that a moderately light resistance slightly above that encountered in normal operation can arrest the roller 2'! and allow the shaft 29 to continue to rotate therein. In this way, even though a jam may be initiated it will not be permitted to progress beyond the early stages due to the operation of the relief mechanism 43, as illustrated in Fig. 2, and withdrawal of the offending sheets can be readily accomplished Without the use of excessive force and without danger of damaging the overrunning clutch orother parts of the machine.

.While improper shingling of the stack is the most frequentcause of jams at the starting roller, other conditions not always clearly understood may produce similar results which will be avoided in any case by application of the principles of the present invention.

The operation of the device is clearly illustrated in Figs. 1 and 2. In Fig. 1 the roller 2'! is shown as rotating in a sheet feeding direction as indicated by the arrow superimposed thereon. Since only one sheet S is being advanced, the pin 49 rests in the recess 5| in shaft 29 and the roller 21 and the shaft 29 turn together in the ordinary manner. When a jam is initiated by the entry of a plurality of sheets S between the surfaces of the roller 21 and the abutment 39, as shown in Fig. 2, the roller 2'! will continue to rotate through a small angle only until the resistance to rotation reaches a value already predetermined. At this point the recess 5| will push aside the end of the pin 49, lifting the same to the surface of the shaft 29 against the force of the spring 53, thus permitting the shaft 29 to rotate inside the stationary roller 2'! and the forward feeding of the sheets S will stop. The jam will thus be arrested in its initial relatively loose condition and before it becomes serious.

Although the relief mechanism above described is found to operate with a high degree of accuracy, its installation can nevertheless be very easily made, the cutting of the recess 5|, drilling the passage 41, insertion of the pin 49 and attachment of the spring 53 by screw 55 being all that is necessary to complete the operation. Furthermore, once proper operation of the relief device has been assured by testing at the installation point, the chance that it will become seriously disarranged is very slight, hence no provision for subsequent adjustment is needed and none is provided. In this way the danger of misfunctioning of the device due to improper adjustment by the operator is likewise avoided.

Having described the invention, what is claimed is:

1. Separating and advancing means for taking one workpiece at a time from a stack of sheet-like workpieces and for feeding the same forward to be worked upon comprising a starting roller; means for driving said roller in a forward feeding direction; an abutment having a surface spaced from the surface of the roller to retard all but the one workpiece to be advanced by the starting roller; and means for automatically disconnecting said roller from its drive when workpiece resistance to roller rotation exceeds a predetermined value.

2. Separating and advancing means for taking one workpiece at a time from a stack of sheet-like workpieces and for feeding the same forward to be worked upon comprising a starting roller; means for driving said roller in a forward feeding direction; an abutment having a surface spaced from the surface of the roller to retard all but the one workpiece to be advanced by the starting roller; and means for preventing a plurality of workpieces from becoming jammed between said roller and said abutment.

3. Separating and advancing means for taking one workpiece at a time from a stack of sheet-like workpieces and for feeding the same forward to be worked upon comprising a starting roller; means for driving said roller in a forward feeding direction; an abutment having a surface spaced from the surface of the roller to retard all but the one workpiece to be advanced by the starting roller; and means for automatically disconnecting said roller from its drive when workpiece resistance to roller rotation exceeds a predetermined value, said means also automatically reconnecting said roller and drive when the workpiece resistance is again reduced below said value.

4. Separating and advancing means for taking one workpiece at a time from a stack of sheet-like workpieces and for feeding the same forward to be worked upon comprising a drive shaft; a starting roller mounted on said shaft; means for driving said shaft in a forward feeding direction; an abutment having a surface spaced from the surface of the roller to retard all but the one workpiece to be advanced by the starting roller; and means connecting said roller to said shaft for rotation therewith, said means automatically releasing said roller from said shaft when workpiece resistance to roller rotation exceeds a predetermined value.

5. Separating and advancing means for taking one workpiece at a time from a stack of sheet-like workpieces and for feeding the same forward to be worked upon comprising a drive shaft; a starting roller mounted on said shaft; means for driving said shaft in a forward feeding direction; an abutment having a surface spaced from the surface of the roller to retard all but the one workpiece to be advanced by the starting roller; and means connecting said roller to said shaft for rotation therewith, said means automatically releasing said roller from said shaft when workpiece resistance to roller rotation exceeds a predetermined value, said last-named means including a rigid abutment surface and a yielding cooperating abutment surface forming a drive connection, one of said cooperating abutment surfaces being on the shaft and the other on said roller.

6. Separating and advancing means for taking one workpiece at a time from a stack of sheet-like workpieces and for feeding the same forward to be worked upon comprising a drive shaft; a starting roller mounted on said shaft; means for driving said shaft in a forward feeding direction; an abutment having a surface spaced from the surface of the roller to retard all but the one workpiece to be advanced by the starting roller; and means for drivingly connecting said roller with said shaft and for releasing the same from driving connection with the shaft when workpiece resistance to roller rotation exceeds a predetermined value comprising a recessed portion of said shaft; a connector movably mounted on said roller for movement between recess engaging and recess clearing positions; and spring means urging said connector towards recess engaging position.

7. Separating and advancing means for taking one workpiece at a time from a stack of sheet-like workpieces and for feeding the same forward to be worked upon comprising a drive shaft; a starting roller mounted on said shaft; means for driving said shaft in a forward feeding direction; an abutment having a surface spaced from the surface of the roller to retard all but the one workpiece to be advanced by the starting roller; and means for drivingly connecting said roller with said shaft and for releasing said driving connection with the shaft when workpiece resistance to roller rotation exceeds a predetermined value comprising a recessed portion of said shaft, a collar integrally connected to said roller and having a radial opening therein in the plane of said recessed portion, a pin slidable in said opening, and a leaf spring mounted on said collar and engaging the outer end of said pin for urging the same towards said shaft.

JOHN WILLIAM BACH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 295,595 Tilton Mar. 25, 1884 1,562,442 Evans Nov. 24, 1925 1,745,738 Carter Feb. 4, 1930 2,224,137 Breman Dec. 10, 1940 2,224,138 Trydal Dec. 10, 1940 

